/*
 * Copyright 2010-2012 Susanta Tewari. <freecode4susant@users.sourceforge.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package bd.org.apache.commons.math.linear;

import bd.org.apache.commons.math.exception.MathParseException;
import bd.org.apache.commons.math.util.CompositeFormat;

import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

/**
 * Formats a vector in components list format "{v0; v1; ...; vk-1}".
 * <p>The prefix and suffix "{" and "}" and the separator "; " can be replaced by
 * any user-defined strings. The number format for components can be configured.</p>
 * <p>White space is ignored at parse time, even if it is in the prefix, suffix
 * or separator specifications. So even if the default separator does include a space
 * character that is used at format time, both input string "{1;1;1}" and
 * " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
 * returned. In the second case, however, the parse position after parsing will be
 * just after the closing curly brace, i.e. just before the trailing space.</p>
 *
 * @version $Id: RealVectorFormat.java 1244107 2012-02-14 16:17:55Z erans $
 * @since 2.0
 */
public class RealVectorFormat {

    /**
     * The default prefix: "{".
     */
    private static final String DEFAULT_PREFIX = "{";

    /**
     * The default suffix: "}".
     */
    private static final String DEFAULT_SUFFIX = "}";

    /**
     * The default separator: ", ".
     */
    private static final String DEFAULT_SEPARATOR = "; ";

    /**
     * Prefix.
     */
    private final String prefix;

    /**
     * Suffix.
     */
    private final String suffix;

    /**
     * Separator.
     */
    private final String separator;

    /**
     * Trimmed prefix.
     */
    private final String trimmedPrefix;

    /**
     * Trimmed suffix.
     */
    private final String trimmedSuffix;

    /**
     * Trimmed separator.
     */
    private final String trimmedSeparator;

    /**
     * The format used for components.
     */
    private final NumberFormat format;

    /**
     * Create an instance with default settings.
     * <p>The instance uses the default prefix, suffix and separator:
     * "{", "}", and "; " and the default number format for components.</p>
     */
    public RealVectorFormat() {

        this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
             CompositeFormat.getDefaultNumberFormat());
    }

    /**
     * Create an instance with a custom number format for components.
     *
     * @param format the custom format for components.
     */
    public RealVectorFormat(final NumberFormat format) {

        this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
    }

    /**
     * Create an instance with custom prefix, suffix and separator.
     *
     * @param prefix prefix to use instead of the default "{"
     * @param suffix suffix to use instead of the default "}"
     * @param separator separator to use instead of the default "; "
     */
    public RealVectorFormat(final String prefix, final String suffix, final String separator) {

        this(prefix, suffix, separator, CompositeFormat.getDefaultNumberFormat());
    }

    /**
     * Create an instance with custom prefix, suffix, separator and format
     * for components.
     *
     * @param prefix prefix to use instead of the default "{"
     * @param suffix suffix to use instead of the default "}"
     * @param separator separator to use instead of the default "; "
     * @param format the custom format for components.
     */
    public RealVectorFormat(final String prefix, final String suffix, final String separator,
                            final NumberFormat format) {

        this.prefix      = prefix;
        this.suffix      = suffix;
        this.separator   = separator;
        trimmedPrefix    = prefix.trim();
        trimmedSuffix    = suffix.trim();
        trimmedSeparator = separator.trim();
        this.format      = format;
    }

    /**
     * Get the set of locales for which real vectors formats are available.
     * <p>This is the same set as the {@link NumberFormat} set.</p>
     *
     * @return available real vector format locales.
     */
    public static Locale[] getAvailableLocales() {

        return NumberFormat.getAvailableLocales();
    }


    /**
     * Get the format prefix.
     *
     * @return format prefix.
     */
    public String getPrefix() {

        return prefix;
    }


    /**
     * Get the format suffix.
     *
     * @return format suffix.
     */
    public String getSuffix() {

        return suffix;
    }


    /**
     * Get the format separator between components.
     *
     * @return format separator.
     */
    public String getSeparator() {

        return separator;
    }


    /**
     * Get the components format.
     *
     * @return components format.
     */
    public NumberFormat getFormat() {

        return format;
    }


    /**
     * Returns the default real vector format for the current locale.
     *
     * @return the default real vector format.
     */
    public static RealVectorFormat getInstance() {

        return getInstance(Locale.getDefault());
    }


    /**
     * Returns the default real vector format for the given locale.
     *
     * @param locale the specific locale used by the format.
     * @return the real vector format specific to the given locale.
     */
    public static RealVectorFormat getInstance(final Locale locale) {

        return new RealVectorFormat(CompositeFormat.getDefaultNumberFormat(locale));
    }


    /**
     * This method calls {@link #format(RealVector, StringBuffer, FieldPosition)}.
     *
     * @param v RealVector object to format.
     * @return a formatted vector.
     */
    public String format(RealVector v) {

        return format(v, new StringBuffer(), new FieldPosition(0)).toString();
    }


    /**
     * Formats a {@link RealVector} object to produce a string.
     *
     * @param vector the object to format.
     * @param toAppendTo where the text is to be appended
     * @param pos On input: an alignment field, if desired. On output: the
     * offsets of the alignment field
     * @return the value passed in as toAppendTo.
     */
    public StringBuffer format(RealVector vector, StringBuffer toAppendTo, FieldPosition pos) {

        pos.setBeginIndex(0);
        pos.setEndIndex(0);

        // format prefix
        toAppendTo.append(prefix);

        // format components
        for (int i = 0; i < vector.getDimension(); ++i) {

            if (i > 0) {
                toAppendTo.append(separator);
            }

            CompositeFormat.formatDouble(vector.getEntry(i), format, toAppendTo, pos);
        }

        // format suffix
        toAppendTo.append(suffix);

        return toAppendTo;
    }


    /**
     * Parse a string to produce a {@link RealVector} object.
     *
     * @param source String to parse.
     * @return the parsed {@link RealVector} object.
     */
    public ArrayRealVector parse(String source) {

        final ParsePosition   parsePosition = new ParsePosition(0);
        final ArrayRealVector result        = parse(source, parsePosition);

        if (parsePosition.getIndex() == 0) {

            throw new MathParseException(source, parsePosition.getErrorIndex(),
                                         ArrayRealVector.class);
        }

        return result;
    }


    /**
     * Parse a string to produce a {@link RealVector} object.
     *
     * @param source String to parse.
     * @param pos input/ouput parsing parameter.
     * @return the parsed {@link RealVector} object.
     */
    public ArrayRealVector parse(String source, ParsePosition pos) {

        int initialIndex = pos.getIndex();

        // parse prefix
        CompositeFormat.parseAndIgnoreWhitespace(source, pos);

        if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
            return null;
        }

        // parse components
        List<Number> components = new ArrayList<Number>();

        for (boolean loop = true; loop; ) {

            if (!components.isEmpty()) {

                CompositeFormat.parseAndIgnoreWhitespace(source, pos);

                if (!CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
                    loop = false;
                }
            }

            if (loop) {

                CompositeFormat.parseAndIgnoreWhitespace(source, pos);

                Number component = CompositeFormat.parseNumber(source, format, pos);

                if (component != null) {
                    components.add(component);
                } else {

                    // invalid component
                    // set index back to initial, error index should already be set
                    pos.setIndex(initialIndex);

                    return null;
                }
            }

        }

        // parse suffix
        CompositeFormat.parseAndIgnoreWhitespace(source, pos);

        if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
            return null;
        }

        // build vector
        double[] data = new double[components.size()];

        for (int i = 0; i < data.length; ++i) {

            data[i] = components.get(i).doubleValue();
        }

        return new ArrayRealVector(data, false);
    }
}
